9 Easy Ways to Troubleshoot a Heater or Furnace Problem

When your gas furnace or heater is malfunctioning, your first instinct might be to pick up the phone and call your HVAC contractor immediately.

That’s understandable, but in some cases it may not be necessary. Here are nine things you should check yourself before you contact the professionals …

#1 Check to see if the thermostat is set to “heat.”

This seems obvious, but if the switch has been accidentally turned off while dusting or cleaning that will prevent the furnace from firing up. Also, you should check the thermostat to make sure it is set high enough to make the furnace come on.

#2 Inspect the HVAC air filter.

A dirty and clogged air filter will inhibit air flow and put excessive stress and strain on your furnace, possibly damaging performance or even causing it to shut down. Clogged air filters should be replaced, not cleaned, and you should avoid purchasing cheap fiberglass filters that won’t deliver adequate performance even when they’re brand new.

#3 Change the batteries on the thermostat.

There should be a flashing light on your thermostat that lets you know if the batteries are running low. But you might have missed it, and if you did your thermostat batteries may be completely drained and in need of replacement.

#4 Make sure the furnace is getting electricity.

On the thermostat there’s a switch for the fan that will be labeled “on” or “auto.” If you switch it on and hear no sound, it could mean you have an electrical problem (which you can’t fix yourself, naturally).

#5 Find and check the circuit breaker.

Open the breaker panel and check to see if the one labeled “furnace” has somehow been turned off, or become stuck in a middle position. If none of the switches are labeled, and one of them is in a different position than the others, switch it on and see if the furnace responds.

#6 Check the furnace switch.

The furnace switch is a silver box with a white switch located on the side of the furnace, or on a nearby wall. If it’s been pushed down by mistake, push it up and wait a couple of minutes to see if the furnace comes back on.

#7 Look for an error code.

Furnaces manufactured after 1990 have a tiny lighted window where an error code is supposed to flash when something goes wrong. There is a key on the inside of one of the furnace’s access panels that will tell you what the various codes mean, and if one is flashing you’ll be able to discover exactly why your furnace isn’t functioning.

#8 Check the pilot light.

Furnaces that were installed more than 20 years ago (give or take a year or two) may still use a pilot light. Should yours be out, your furnace’s instruction manual will tell you how to safely relight it.

#9 Make sure the gas valve is on.

Presumably, the gas valve (you can find it somewhere within a few feet of the furnace) will never be touched. But you should at least look at it to see if it is in the proper position (turned horizontally instead of vertically, which allows the gas to flow). Another clue is if you have another gas appliance in the home, and it isn’t working, that could mean your gas has been cut off.

If none of these do the trick, or reveal something you know you can’t fix, that would be the time to summon the experts.

Need Gas Furnace Repair or Inspection Services? Call Us Today

When you need an expert to check or repair your gas furnace in the Denver Metro Area, your smartest choice is to contact Northern Climate Control immediately. Our trained and certified technicians can diagnose any problem and fix it quickly, affordably, and reliably—and they can offer you superior maintenance and inspection services as well, which is your best bet for avoiding furnace trouble. Northern Climate Control knows gas appliances, and we know how vital they are to your home comfort and safety during those long, cold Rocky Mountain winters.